AEROBIC FITNESS INFLUENCES THE RESPONSE OF MAXIMAL OXYGEN-UPTAKE AND LACTATE THRESHOLD IN ACUTE HYPOBARIC HYPOXIA

We studied 12 highly trained athletes, 6 male ice-hockey players and 6 cross-country skiers (2 females, 4 males). All of them participated i n a maximal electrically braked bicycle ergometer test in a hypobaric chamber at the simulated altitude of 3000 m (520 mmHg) and in normobar ic conditions two days apart in random order. The maximal oxygen uptak e was 57.4 +/- 7.1 (SD) ml/kg/min in normobaria (VO(2max)norm) and 46. 6 +/- 4.9 (SD) ml/kg/min in hypobaric hypoxia (VO(2max)hyp). The decre ase in maximal oxygen uptake (Delta VO2max) at the simulated altitude of 3000 m correlated significantly (p < 0.05, r = 0.61) to the maximal oxygen uptake in normobaric conditions VO(2max)norm). The lactate thr eshold was 43.5 +/- 6.4 (SD) ml/kg/min in normobaria (VO(2LT)norm) and 36.5 +/- 4.2 (SD) ml/kg/min in hypobaric hypoxia (VO(2LT)hyp) The dec rement (Delta VO(2)LT) of lactate threshold in hypoxia correlated sign ificantly (p < 0.01, r = 0.68) with the lactate threshold in normobari c conditions (VO(LT)norm). Thus we observed the largest reduction of b oth maximal oxygen uptake and lactate threshold during exercise at hyp obaric hypoxia in the most fit athletes.